Which of the following is NOT a type of relationship column type?

A relationship column type is primarily associated with how entities in a database connect to one another, specifically regarding how data in one table relates to data in another. Foreign keys and many-to-many relationships are standard methods of establishing these connections in relational databases.

Foreign keys serve to link one table to another, ensuring referential integrity by requiring that a value in one column must match a value in another related column. Many-to-many relationships allow for a more complex interaction where multiple records in one table can correspond to multiple records in another, often facilitated through a junction table.

Arrays, while they can represent a collection of values, typically do not establish a defined relational structure between tables. However, they can be used in certain implementations to handle lists of values. In contrast, static arrays are not recognized as a standard type of relationship in relational database design, as they do not facilitate any form of data linkage or relationship between entities. Instead, static arrays simply hold a predetermined size of elements and do not relate to the concept of linking tables in a relational manner.

Therefore, identifying static arrays as not being a type of relationship column type stems from the understanding that they lack the essential relational capabilities necessary to define connections between different tables within a database.